1. Field of the Invention
The present invention relates to a non-random starch hydrolysis process for preparing low D.E. starch hydrolysates and low D.E. starch conversion products, also known as low D.E. maltodextrins. D.E. is an abbreviation for dextrose equivalent, which is a common expression in the art for describing the total reducing sugars content of a material, expressed as percent dextrose, dry basis. The invention also has to do with the low D.E. maltodextrins themselves and to compositions employing them, such as fat mimetics and bulking agents.
2. Description of Related Art
Low D.E. starch hydrolysates and starch conversion products are known in the art. Generally they are produced by the hydrolysis of starch with acids or enzymes. Such products have a bland taste, low sweetness and low hygroscopicity and are useful for a variety of food applications. For example, they are useful as bulking agents, carriers, film-forming agents, encapsulating agents and the like.
Typical of the early processes for preparing low D.E. starch hydrolysates are those described in U.S. Pat. Nos. 3,853,706 and 3,849,194. Both patents describe processes utilizing certain bacterial alpha-amylases to treat starch hydrolysates and provide products having a D.E. between 5 and 20-25.
U.S. Pat. No. 4,284,722 discloses the use of an alpha-amylase derived from Bacillus stearothermophilus to hydrolyze starch at a pH between 3.5 and 6.5 and a temperature between 100 and 115.degree. C. for 160 minutes. Thereafter the temperature is dropped to 80.degree.-100.degree. C. prior to subsequent treatment with additional enzymes to prepare various end products.
U.S. Pat. No. 3,756,919 discloses the use of molecular extrusion to reduce a starch hydrolysate having a D.E. of from about 20 to about 43, to from about 5 to about 18. Molecular extrusion is an essential technique in that patent since the product being separated does not have a sharp differentiation in molecular size. The use of extrusion separation techniques is also described in U.S. Pat. Nos. 4,109,075 and 4,840,807.
The known methods of starch hydrolysis by acids or enzymes cause random cleavage of the starch molecules. This results in the formation of linear and branched fragments of various chain lengths and properties. Depending on the chain length and degree of branching present, the resulting starch hydrolysate may be soluble or insoluble in water, may or may not be resistant to hazing, and so forth. Accordingly, a method of starch cleavage having more specificity is needed to prepare starch hydrolysates having more uniform and predictable qualities.
Various low D.E. maltodextrins are available commercially. For example, Maltrin M040 maltodextrin, available from Grain Processing Corporation, Muscatine, Iowa, is disclosed to have a D.E. of approximately 4-7. Nevertheless, there is a need for low D.E. hydrolysates having high concentrations of high molecular weight, branched molecules and having a reduced amount of high molecular weight linear molecules and low molecular weight linear or branched molecules. A means of making such low D.E. hydrolysates has now been developed according to the present invention. The hydrolysates of the invention have improved properties over other types of low D.E. hydrolysates such as lower color, higher clarity and cleaner taste than currently available products, and could be used in new applications such as stable, low D.E. syrups.